This invention generally relates to the field of particle collection and transfer. The invention provides a method and apparatus for collecting a quantity of cells from a biological sample and transferring the cells onto a glass slide. The invention is useful in cytology, which is a medical and laboratory science that makes diagnoses based on findings in cells.
A typical cytological technique is a "Pap smear" test, which is used in one instance to detect abnormal cells in a woman's cervix before they develop into cancer cells. The technique can also be used to aid in the detection of disease in other organs of the body.
Cytology is less invasive to a patient than traditional surgical pathological procedures, e.g. biopsy. All that is required for cytology is that a sample of cells be obtained from the patient, which can typically be done by scraping or swabbing an area, as in the case of cervical samples, by procuring fluids from body sites such as the chest cavity, bladder, or spinal canal, or by needle aspiration. After a solution containing cells is obtained using one of these techniques, the cells are collected from the solution and transferred onto a glass slide for viewing.
This processing of the cells typically requires that the cells be separated from one another, i.e. dispersed, so that individual cells can be transferred to the glass slide for visual examination. In addition, the dispersed cells are counted so that a generally known quantity of the cells can be transferred to the slide for the visual examination. The phrase "visual examination" is used herein in a broad context and includes human visual inspection as well as machine image inspection. It also includes inspection with various types of illumination. Also, practice of the invention can include procedures, such as staining, conventionally performed between collecting the cells and the actual examination.
It is important for effective visual examination that the cells have a proper spatial distribution. This enables individual cells to be examined. Ideally, this means that a single layer of cells is collected and transferred to the glass viewing slide.
Prior techniques for dispersing cells and for collecting a measured quantity of the cells; and for transferring them to an optical slide for visual examination, have several disadvantages. These include shortcomings such as requiring costly equipment, being time-consuming, requiring undue operator attention, being subject to inter-sample contamination, and providing limited performance in terms of reliability, repeatability, accuracy and precision. The prior techniques also present bio-hazard risks from the handling of the sample. These disadvantages are increasingly significant with the increasing use of cytologic diagnosis.
It is an object of this invention to provide an apparatus and method for quickly and efficiently collecting a selected quantity of dispersed cells from a sample solution. It is also an object of the invention to provide such an apparatus and method for transferring the cells onto a glass slide for visual examination with a uniform single-layer distribution.
A more specific object is to provide such a method and apparatus capable of automated operation with minimal operator attendance and yet with relatively high reliability, repeatability, accuracy, and precision as well as with low inter-sample contamination.
A further object is to provide such an apparatus and method that handle the specimen in a manner that presents low bio-hazard risks.
Another object of the invention is to provide such automated apparatus, for preparing cells for visual examination, that attains high inter-sample isolation with a minimal number of disposables and at relatively low cost.
Other objects of the invention will in part be obvious and will in part appear hereinafter.